Photographing developing and fixing solution



Patented Nov. 9, 1943 I rno'roomnmo DEVELOPING AND nxmo som'non Martin Solo, Rochester, N. Y., and John W.

Hench, West Lafayette, Ind., assignors to Eastman Kodak Company, Rochester, N. Y.. a corporatlon or New Jersey I i No Drawing.

' This invention relates 'to processing solutionsfor photographic layers of cellulose ethers, containing silver-salts in the body oi. the layer.

Photographic layers or cellulose ether containing about 39' per cent ethoxyl to about 53 per cent ethoxylcontaining a light sensitive silver salt, process very .slowly in the usual aqueous developing and fixing .solutions.

Application November as, 1941, Serial No. 420,868

.tor example, 45% (by weight) methanol, 35%

iso-propanol or ethanol, or 30% n-p'ropanol are satisfactory. V

4 I Ema: 2

Fixing solution To a solution of 20 grams of sodium thiosulfate in so cc. or water are added 100 grams of metha- We have found that the rateof penetration of aqueous developing and fixing solutions may be considerably increased by diluting standard'developing and fixing solutions with certain water miscible organic compounds which have a pronounced swelling action on the cellulose ethers.

It is, therefore, the object of the present invention to provide'developing and 'flxing solutions which permit the dissolved developing or fixing salts to penetrate readily a cellulose ether layer having an alkox'yl content of about 39 to 53 percent. 1

This object is accomplished by incorporating in a developing or fixing solution a swelling agent for cellulose ether.

The method we use is to take a standard developing or fixing solution and dilute it to the required strength with'water and at the same time add to it a sumcient quantity ofan organic swelling agent to decrease the time of penetration of the solution. Among the swelling agents which have been found suitable for use in developing and fixing solutions are: methanol, ethanol, propanol, isopropanol, tertiary butanol, ether alcohols such as p-ethoxy ethanol etc. Ketones, such as acetone, are also useful.

The following examples of developing and fixing baths, are formulated accordin to our invention and it is to beunderstood that they are for-the purpose of illustration only.

- Emmett l In the preparation or the above solution a liter of a stock developer i diluted as required, for instance, with four volumes ot,water in processing photographic papers, and then an alcohol is added. The optimum amount or alcohol in the developer depends upon the particular alcohol used,

nol. If other alcohols are used instead=of methanols, either 63 grams ethanol, 38 -grams isopropanol, or 13 grams n-propanol or tertiary butanol are addedin the place of methanol. A ketone such as acetone, in the amount of 45 grams, may also be used with satisfactory results.

The solutions used according to our invention are of value in treating many types of cellulose ether emulsion, asfor instance those containing, ethyl, propyl and butyl cellulose etc., mixed ethers containing two or more alkoxyl groups such as ethyl propyl or ethyl butyl celluloses,

especially mixed ethers, such as those having a large share or ethoxyl and a minor proportion of propoxyl, butyoxyl etc. if such ethers are within the proper range of etherification so. as to be permeable to the processing solutions of the invention. Thus the cellulose ethyl ethers rang ing in alkyoxyl content from practically completely etherified ethers to those ethers contain ing about 39 per cent 'alkoxyl -(less than two alkoxyl groups per Cs cellulose unit) may be treated with the solutions of our invention. Where the degree of etheriflcationis less than about 39 per cent alkoxyl', the layer is more ermeable to water than the more completely etherifled ethers, and while it may not be necessary to use the solutions of our invention in processing such layers, the solutions maybe used, in which case the alcohol or ketone content of the solutions is decreased. Similarly, tests will indicate the proportion of alcohols to be used in processing emulsion layers of higher ethers or mixed ethers of cellulose.

In processlngcellulose ether layers of about 39 to 53 per cent ethoxyl containing an exposed silver salt, the developing solution of the invention reduces the'exposed salt to silver in the region of the exposure. The fixing solution used thereafter removes the unexposed silver salt fromthe' layer. Other developing and fixing solutions containing the swelling agents of the invention may be used, such as developers containing other developing agents, fog inhibitors, preservatives, etc., and

fixing solutions containing other fixing agents, v

hardeners, etc.

By the term "ethoxyl" as used herein, we mean the alkoxyl content of those cellulose ethyl ethers containing only ethoxyl, and of those cellulose ethers containing a, major share of ethoxyl and a minor proportion of propoxyl, butoxyl or similar group.

It is to be understood that the disclosure herein is by way of example, and that we consider as included in our invention all, modifications and equivalents falling within the scope of the appended claim.

t we claim i The method oi processing an exposed photographic emulsion of silver halide dispersed in a cellulose ethyl ether having an ethoxyl content of about 39 percent to about 53 percent, and tree of gelatin, which comprises treating said exposed emulsion in turn with developing and fixing baths, at least one of said baths containing a substantial amount of a water-soluble monohydroxy alcohol, said alcohol acting as a swelling agent for the cellulose ether and thereby decreasing the time required to process said cellulose ether emulsion.

MARTIN SALO. JOHN W. MENCH. 

